全文获取类型
收费全文 | 557篇 |
免费 | 26篇 |
专业分类
电工技术 | 24篇 |
综合类 | 3篇 |
化学工业 | 169篇 |
金属工艺 | 19篇 |
机械仪表 | 18篇 |
建筑科学 | 13篇 |
能源动力 | 19篇 |
轻工业 | 56篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 48篇 |
一般工业技术 | 100篇 |
冶金工业 | 22篇 |
原子能技术 | 17篇 |
自动化技术 | 73篇 |
出版年
2023年 | 12篇 |
2022年 | 23篇 |
2021年 | 27篇 |
2020年 | 12篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 14篇 |
2016年 | 20篇 |
2015年 | 10篇 |
2014年 | 27篇 |
2013年 | 48篇 |
2012年 | 30篇 |
2011年 | 53篇 |
2010年 | 31篇 |
2009年 | 19篇 |
2008年 | 21篇 |
2007年 | 24篇 |
2006年 | 16篇 |
2005年 | 10篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 14篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1972年 | 3篇 |
1970年 | 1篇 |
排序方式: 共有583条查询结果,搜索用时 15 毫秒
41.
Kolmogorov introduced the concept of -entropy to analyze information in classical continuous systems. The fractal dimension of a geometric set was introduced by Mandelbrot as a new criterion to analyze the geometric complexity of the set. The -entropy and the fractal dimension of a state in a general quantum system were introduced by one of the present authors (MO) in order to characterize chaotic properties of general states.In this paper, we show that -entropy of a state includes Kolmogorov's -entropy, and that the fractal dimension of a state describes fractal structure of Gaussian measures. 相似文献
42.
Wei Zhou Chak Wah Tang Jia Zhu Kei May Lau Zeng Y. Liu H.G. Tao N.G. Bolognesi C.R. 《Electron Device Letters, IEEE》2007,28(7):539-542
Good-quality metamorphic InP buffer layers have been successfully grown on GaAs substrates by metal-organic chemical vapor deposition. Characterization by atomic force microscope, transmission electron microscopy, high-resolution X-ray diffraction, and Hall measurements indicated that the layers are of high crystalline quality, good mobility, and excellent surface morphology. On this buffer, we demonstrated the first metamorphic InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) with good material quality and device performance. Metamorphic DHBTs showed direct-current and radio-frequency characteristics that are comparable to those grown on lattice-matched InP substrates. 相似文献
43.
Xiujun Gong Kensuke Nakamura Hua Yu Kei Yura Nobuhiro Go 《IEEE transactions on information technology in biomedicine》2007,11(4):428-434
The emerging grid computing technologies enable bioinformatics scientists to conduct their researches in a virtual laboratory, in which they share public databases, computational tools as well as their analysis workflows. However, the development of grid applications is still a nightmare for general bioinformatics scientists, due to the lack of grid programming environments, standards and high-level services. Here, we present a system, which we named Bioinformatics: Ask Any Questions (BAAQ), to automate this development procedure as much as possible. BAAQ allows scientists to store and manage remote biological data and programs, to build analysis workflows that integrate these resources seamlessly, and to discover knowledge from available resources. This paper addresses two issues in building grid applications in bioinformatics: how to smoothly compose an analysis workflow using heterogeneous resources and how to efficiently discover and re-use available resources in the grid community. Correspondingly an intelligent grid programming environment and an active solution recommendation service are proposed. Finally, we present a case study applying BAAQ to a bioinformatics problem. 相似文献
44.
Eiji Takeda Takao Watanabe Shinichiro Kimura Jiro Yugami Keiichi Haraguchi Kei Suzuki Katsuro Sasaki 《Microelectronics Reliability》2000,40(6)
The progress of silicon technology is opening the era of “systems on silicon” in which a large-scale memory, a CPU, and other logic macros will be integrated on a single chip. These kinds of chips, called system LSIs, have an especially promising future in mobile and multimedia applications but face inherent technical problems related to the reliability of ultrathin oxide film, conflict in the processing of different components, increased gate and subthreshold leakage currents, memory bottlenecks, and design complexity. This paper reviews the system LSIs and then introduces related technologies in processing, circuits, chip architecture, and design. It also discusses the influence of the system LSIs on business strategies. 相似文献
45.
Yuji Yabuki Yoshitaka Mukaida Yoshinori Saito Kazunori Oshima Tatsuo Takahashi Eiichi Muroi Kei Hashimoto Yasushi Uda 《Food chemistry》2010
To characterise the composition of sulphur-containing constituents in Chinese chive (Allium tuberosum Rottler), GC–MS and HPLC analyses were carried out, using 12 varieties of Chinese origin, 4 varieties of Japanese origin and 6 commercially available cultivars. Five disulphides (dimethyl, allyl methyl, methyl 1-(E)-propenyl, diallyl, and allyl 1-(E)-propenyl), two trisulphides (dimethyl and allyl methyl), and two vinyldithiins (3-vinyl-[4H]-1,2- and 2-vinyl-[4H]-1,3-) were identified on the basis of their mass spectral and GC-retention data. Among the detected sulphur compounds, sulphides with a methyl group predominated over those with an allyl group. This was supported by the HPLC estimations, suggesting that all cultivars examined had much greater amounts of methiin than alliin. Also, two novel compounds were tentatively identified as [3H,4H]-1,2-dithiin and [2H,4H]-1,3-dithiin on the basis of their mass spectral features, GC-retention data, and some experimental results on their formation in reaction mixtures with different proportions of methiin and alliin. Their formation mechanism was proposed. 相似文献
46.
Kazuaki Yanagisawa Keishiro Ito Chisato Katsuki Kei Kawashima Masashi Shirabe 《Scientometrics》2010,84(3):563-573
An outcome of nuclear safety research (NSR) done by JAERI (Japan Atomic Energy Research Institute) was case studied by the
bibliometric method. (1) For LOCA (loss-of-coolant accident) a domestic share of JAERI in monoclinic research paper was 63%
at the past (20) 1978–1982 but was decreased to 40% at the present 1998–2002. For co-authored papers a domestic share between
JAERI and PS (public sectors) was zero at past (20) but increased to 4% at the present. Research cooperation is active between
Tokyo University and JAERI or between JAERI and Nagoya University. (2) It is revealed that LOCA outputs born by NSR-JAERI
reflected partly to those of the Safety Licensing Guidelines, however, a share of NSR-JAERI could not determined due to the
lack of necessary information in the Guideline. 相似文献
47.
Masahide Goto Kei Hagiwara Yoshinori Iguchi Hiroshi Ohtake Takuya Saraya Hiroshi Toshiyoshi Toshiro Hiramoto 《IEEJ Transactions on Electrical and Electronic Engineering》2014,9(3):329-333
We have developed a novel MOSFET that can transfer signals vertically without through‐silicon vias but by using a fully depleted silicon‐on‐insulator (FDSOI) structure with its source region connected to the back electrodes as well as the front ones. A prototype MOSFET fabricated using the backside anisotropic wet etching technique has confirmed that the electrical characteristics measured from the front and the back electrodes are identical. The subthreshold factor S of the prototype was found to be 64.5 mV/decade, suggesting a good switching performance. Since the double‐sided MOSFET has vertical signal‐transfer capability and excellent operating characteristics, it is expected to contribute to developing a More‐than‐Moore type device of three‐dimensional integration such as pixel‐parallel image sensors. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
48.
Toda K Ohira S Tanaka T Nishimura T Dasgupta PK 《Environmental science & technology》2004,38(5):1529-1536
We describe a membrane-based collection/analysis system that differentially monitors H2S and CH3SH, and to which a conductometric SO2 analyzer using the same collector was coupled. A diffusion scrubber (DS) comprised of a Nafion tube collects H2S selectively while a porous polytetrafluoroethylene (pPTFE) DS collects both H2S and CH3SH. Both gases are measured via their ability to react with fluorescein mercuric acetate (FMA) which results in decreased fluorescence. The limited dynamic range of a negative signal procedure was overcome by using dual DS units comprised of short and long scrubbers, placed serially in the liquid flow line. Different DS designs and membrane materials were investigated. H2S, CH3SH, and SO2 from a biogenic point source were continuously measured, and the H2S/CH3SH data compared well with a standard procedure involving Tedlar bag collection, preconcentration and thermal desorption from a Tenax trap, and measurement by gas chromatography/flame photometric detection. Walkaround portability of the instrument and very large dynamic range measurement of H2S and SO2 were demonstrated around the Mt. Aso volcano. 相似文献
49.
A semi-continuous fluidized-bed process is reported which rapidly converts acetylene into carbon nanotubes (CNTs). Catalysts are first immobilized on ceramic beads and CNTs are then grown on the beads and then separated from them in a repetitive process accomplished within a single reactor simply by switching gases at a fixed temperature. CNTs of 6–10 nm diameter, three walls on average, 0.4 mm length and 99 wt.% purity were synthesized at an yield of over 70% in a reactor residence time shorter than 0.3 s. The easy and efficient production of such CNTs with in situ separation from the catalysts may accelerate the development of CNT-based nanotechnology industries. 相似文献
50.